# 四大基础数据结构的CRUD操作
# Create
s = ["a", "b"]
s.append(["c","d"])
s.append((1,2))
s.append({"a":2})
s.append({1,2,3})

s = ["a"]
s_1 = (1,2,3)
s_2 = {"a":2}]
s_3 = {1,2,3}
s += s_1
s += s_2
s += s_3
s.insert(0, "b")

# Retrieve
s = ["a", "b", "c","d"]
a = s[0]
b = s[:-1:1]
c = s.index("b")

# UPDATE
s = ["a", "b"]
s[0] = "c"
s[0:2] = ["d", "e"]

# DELETE
s = ["a", "b","c"]
a = s.pop(0)
# 移除列表中的所有项
s.clear()



